Refrigerant circulating system



N 1949 M. G. SHOEMAKER ET AL 2,489,680

REFRIGERANT C IRCULAT ING SYSTEM Filed May 15. 1946 INVENTORJ' MALCOLM G Sf/OZMAKER All? AUIIELL M HALL W/Z/WW Patented Nov. 29, 1949 UNITED STATES PATENT- OFFICE 2,489,880 nnmrcrzaan'r cmcum'rmc' SYSTEM Malcolm G. Shoemaker, Abington, and Russell M. Hall, Philadelphia, Pa., assignors, by mesne as-. signmenis, to Philco Corporation, Philadelphia, Pa., a corporation of Pennsylvania Application May 15, 1946, Serial No. 669,964

2 Claims.

This invention relates to refrigeration and more particularly to refrigerant circulating systems.

The primary object of the invention is to provide an improved refrigerant circulating system.

More specifically, it is an important feature of the invention to provide an improved refrigerant circulating system wherein any gaseous refrigerant is bled from the evaporator supply line prior to entrance into the evaporator, thus insuring that substantially all of the refrigerant, flowing into the evaporator, will be in the liquid phase.

Another object of the invention is to provide a refrigerant circulating system wherein a more uniform quantity of liquid refrigerant may be fed to each of a plurality of evaporators, from the same supply line.

Yet another object is the provision of such a refrigerant circulating system wherein blowthrough of the evaporator, during the off-cycle of compressor operation, is substantially prevented.

Still further it is an object of the invention to provide such apparatus, further characterized by its simplicity and inexpensive design.

The invention has been found particularly useful in systems utilizing continuous tube evaporators and especially where more than one of such evaporators are connected in a system of the capillary restriction type. It should be clearly understood, however, that its use is not intended to be limited to such systems, as it may be used with facility in many systems wherein it is desired to separate the gaseous from the liquid refrigerant.

A preferred embodiment of the invention has been illustrated in the accompanying drawings, wherein:

Figure 1 is a somewhat diagrammatic illustration of a refrigerant circulating system embodying the present invention;

Figure 2 is a vertical sectional view of an element of the invention; and,

Figure 3 is a sectional view taken substantially along the line indicated at 3-3 in Figure 2.

With further reference to the drawings, and particularly to Figure 1 thereof, there is illustrated a refrigerant circulating system of the type comprising a hermetically sealed compressor II, a condenser I 2, and a continuous tube evaporator I 3, all connected in series flow circuit, such connection being eflected by conduit i4 connecting the outlet of the compressor with the inlet of the condenser, capillary tube restrictor 2 l5 connecting the outlet of the condenser with the inlet of the evaporator, and by suction conduit II connecting the outlet of the evaporator with the inlet of the compressor.

Compressor II and condenser |2 are of conventional design and no detailed description is needed here. However, it should be understood that, while a hennetically sealed compressor has been illustrated, other types may be as readily used.

Evaporator l3, as explained heretofore, may be of any suitable type but is preferably of the continuous tube type and may comprise either a single tube or coil, or a plurality of tubes or coils, each supplied with refrigerant from the same supply line. For the sake of clarity, however, the drawings have been confinedto illustrating a single evaporator comprising a pair 'of continuous coils i1 and I8, each of which is wrapped in a serpentine path around a portion of the evaporator shell I9, at opposite ends thereof. These coils are provided with inlet extensions 2|! and 2| respectively, while the outlet ends 22 and 23, respectively, each terminate in a common suction header 24 from which the spent refrigerant is conducted to the compressor through suction conduit Hi.

In particular accordance with the present invention there is interposed between the outlet of capillary restrictor I5 and inlet ends 20 and 2| of the evaporator coils, a means 25 for separating the gaseous from the liquid refrigerant, and for by-passing the gaseous refrigerant around the evaporator directly to the low, or suction side of the system.

Means 25 includes a hermetically sealed cylindrical chamber which preferably comprises an elongate, inverted, cup-shaped member 26 having its open end closed by a cap or cover member 21 suitably secured thereto in fiuidtight relation therewith, as by welding. As more clearly seen in Figure 2, the inlet extensions 20 and 2| of evaporator coils l1 and I8 are in open communication with the interior of the chamber, being secured in cover 21.

Still making reference to Figure 2, a conduit 28 is shown' extending through the center or bottom wall or cover 21, into chamber 25, said conduit having its end terminating within said chamber in open communication therewith, at a point adjacent the top wall thereof 29. The other end of the conduit terminates within suction header 24, thus providing an open passage between the top of the chamber and the header. Conduit 28 is shown passing through cover 27,

33 but it'should be understood that it could be connected through member 28, the important feature being that it is arranged to conduct gaseous refrigerant from the top portion of the chamber to the suction line.

With reference to Figure 3 it is seen that the outlet end of capillary tube I5 is tangentially secured to the side wall of chamber member 2e and in open communication with the interior thereof, preferably at a point spaced from the bottom wall 21 a distance equal to approximately one-third the total vertical dimension of the chamber. This position is well suited for the purposes of the invention, for reasons brought out later.

In the operation of the usual capillary restrictor type of system, gaseous refrigerant from the compressor is forced into the condenser wherein it is condensed and from which the resultant liquid is forced at high velocity through the capillary restrictor tube into the evaporator, in which it expands and evaporates, thence returnin to the compressor through the suction line. As will be recognized, under certain operating conditions, the refrigerant forced through the capillary restrictor will include some residual gas, which was not liquified in the condenser. As brought out hereinafter, entrance of this gas into the evaporator reduces the effectiveness of the system. Also, it is customary in this type of system to arrange the capillary and the suction line in intimate heat exchange relation so that heat from the refrigerant passing through the capillary will be transferred to the cold gaseous refrigerant passing through the suction line, however, for clarity of illustration, this arrangement has not been shown in the drawings of the present invention. Even with this arrangement there is a certain amount of flash gas generated in the capillary tube.

Such residual and flash gas, as well as that flash gas generated by the heat of liquid at the moment of expansion from the small diameter capillary tube into the larger diameter evaporator tubing, occupy an appreciable volume in the evaporator and displace a like volume of liquid refrigerant, thus reducing the effective heat absorbing capacity of the evaporator.

The apparatus of the present invention substantially prevents gaseous refrigerant-arising from any cause-from entering into and passing through the evaporator, while still permitting unimpeded flow of liquid refrigerant thereinto. This is accomplished in the following manner:

The tangential arrangement of the capillary tube with chamber 26 causes the mixture of gaseous and liquidrefrigerant entering the chamber to swirl or spin around the inner wall at high velocity as in a centrifuge, thus causing the gaseous portion thereof to be separated from the liquid and to rise through the generally central portion of the chamber to the top thereof, from whence it is drawn off through conduit 28 directly to suction header 24 of the evaporator. gaseous refrigerant by-passes the evaporator and, in effect, is returned directly to the compressor. The swirling liquid, which substantially fills the lower portion of the chamber, is drawn into evaporator coils H and I8 through inlet extensions and 2| thereof.

As mentioned above, the level at which the capillary tube inlets into the separating chamber is preferably maintained in the region of the lower portion of said chamber.

By virtue of such location, the stream of incoming liquid '28 be formed as a restrictor, to

r 4 V I V serves to malntain a swirling motion of the liquid already in the chamber, which motion is required for proper centrifuging. The optimum inlet levelwill vary in different specific embodiments,

but is susceptible of ready determination.

In the embodiment illustrated, and as would generally be the case, the flow-resistance offered by the conduits 20 and 2| and their associated evaporator tubing, would be considerably in excess of the resistance offered by the relatively short conduit 2| leadin to the suction header, if similar tubing were used throughout. As a consequence, since these conduits comprise parallel paths, such an embodiment requires that conduit prevent the separated liquid from by-passing the evaporator, by flowing through said conduit '28 directly to the suction header. Although many factors in the system will have a bearing on the amount of restriction required, it may be mentioned that six inches of 0.050" I. D. capillary tubing has given highly satisfactory results in one representative system. In general, the restriction of conduit 28 should be such that the liquid level is maintained below the upper, inlet end of conduit 28, and

therefore such that only gaseous refrigerant flows through said conduit 28.

From the foregoing it is apparent that the present invention provides an extremely simple and inexpensive apparatus providing an improved refrigerant circulating system wherein the major portion of the gaseous refrigerant is bled from the supply line prior to the entrance of the refrigerant into the evaporator, whereby to supply the latter with a larger proportion of refrigerant in the liquid state.

Also, when the compressor ceases operation a quantity of uncondensed high pressure refrigerant remains in the condenser and, because the system is of the continuously open type, this reirigerant will continue to flow until the pressure throughot the system has equalized. Due to the immediate pressure drop in the condenser the refrigerant remains in its gaseous state and in the usual system of this type, not equipped with the present invention, it tends to blow-through the evaporator, i. e., blow the liquid refrigerant from the evaporator in the process of equalizing the pressure throughout the system, thus leaving the evaporator in a starved condition during the off-cycle. With the present invention a considerable portion of this gaseous refrigerant is by-passed around the evaporator through restrictor conduit 28 to thus relieve the blowthrough condition without substantially disturbing the liqid content of the evaporator.

We claim:

1. In a refrigerant circulating system, a condensing unit, an evaporator, refrigerant flow control means through which gaseous and liquid refrigerant flow from said unit toward said evaporator at high velocity, means interposed between said first-mentioned means and said evaporator for receiving said refrigerant and operative to effect centrifugal separation of the gaseous portion thereof from the liquid, means for conducting the gaseous portion to said unit, and means for delivering the liquid portion to said evaporator.

2. A refrigerant circulating system comprising a condensing unit, an evaporator, a restrictor tube through which gaseous and liquid refrigerant flow from said unit toward said evaporator, said tube being effective to cause the refrigerant to flow therethrough at high velocity, means interposed between said tube and said evaporator for receiving said refrigerant, said means being operative to effect centrifugal separation of the gaseous portion from the liquid, means for conducting the gaseous refrigerant to said unit, and means for delivering said liquid refrigerant to said evaporator.

, circular path at the bottom of said chamber where the centrifugal force separates the gaseous portion from the liquid and permits the gaseous portion to be drawn through the conducting means to said unit and the liquid refrigerant to '-be drawn into said evaporator through said delivering means.

5. In a refrigerant circulating system comprising a compressor, a condenser, and an evaporator, in series flow circuit, apparatus for separating intermixed gaseous and liquid refrigerant flowing at high velocity from said condenser toward said evaporator, said apparatus comprising a cylindrical chamber in which said refrigerant is received in a mannerto cause it to swirl rapidly around its interior wall to thus cause centrifugal separation of the liquid refrigerant from the gaseous, means communicating with one portion of said chamber for delivering the liquid refrigerant to said evaporator, and means in communication with another portion of said chamber for drawing of! the gaseous refrigerant and conducting it to said compressor.

6. In a refrigerant circulating system comprising a compressor, a condenser, and an evaporator, in series flow circuit, apparatus for septhereof and thus causing it to swirl rapidly around said wall to centrifugally separate the liquid refrigerant from the gaseous, means adjacent the bottom of said chamber for delivering the liquid to said evaporator, and means adjacent the top of said chamber for drawing on. the gaseous refrigerant and conducting it to said compressor.

7. A refrigerant circulating system comprising a condensing unit, an evaporator including means providing for inflow of liquid refrigerant and a header within which gaseous refrigerant is accumulated, a restrictor tube through which gaseous and liquid refrigerant flow from said unit toward said evaporator, means interposed between said restrictor tube and said evaporator for separating the gaseous from the liquid refrigerant, means for conducting the gaseous refrigerant to said header, and-means for delivering the liquid refrigerant to said inflow means.

' MALCOLM G. SHOEMAKER.

RUSSELL M. HALL.

REFERENCES CITED The following references are of record in thefile of this patent: v 1

UNITED STATES PATENTS 

